Age range of formation of sedimentary-volcanogenic complex of the Vetreny Belt (the southeast of the Baltic Shield)

详细

As a result of studying the Vetreny Belt greenstone structure (the southeast of the Baltic Shield), zircons from terrigenous deposits of the Toksha Formation, underlying the section of the sedimentary-volcanogenic complex, and zircons of the Vetreny Belt Formation, deposits of which crown the section, were dated. The results of analysis of age data of detrital zircons from quartzites of the Toksha Formation indicate that Mesoarchean greenstone complexes and paleo-Archean granitogneisses of the Vodlozero Block (Karelia) were the provenance area from which these zircons were derived. The occurrence of the youngest zircons with age of 2654.3 ± 38.5 Ma is evidence that the formation of the Vetreny Belt, including the Toksha Formation, began no earlier than this time. Zircons from volcanic rocks of the Vetreny Belt yielded the age of 2405 ± 5 Ma. Thus, the age interval of the formation of the sedimentary-volcanogenic complex of the Vetreny Belt ranges from 2654.3 ± 38.5 to 2405 ± 5 Ma.